The Bretton Woods system sought to secure the advantages of the gold standard without its disadvantages. Thus, a compromise was sought between the polar alternatives of either freely floating or irrevocably fixed rates—an arrangement that might gain the advantages of both without suffering the disadvantages of either while retaining the right to revise currency values on occasion as circumstances warranted.

The rules of Bretton Woods, set forth in the articles of agreement of the International Monetary Fund (IMF) and the International Bank for Reconstruction and Development (IBRD), provided for a system of fixed exchange rates. The rules further sought to encourage an open system by committing members to the convertibility of their respective currencies into other currencies and to free trade.

What emerged was the “pegged rate” currency regime. Members were required to establish a parity of their national currencies in terms of gold (a “peg”) and to maintain exchange rates within plus or minus 1% of parity (a “band”) by intervening in their foreign exchange markets (that is, buying or selling foreign money).

In theory the reserve currency would be the bancor, suggested by John Maynard Keynes; however, the United States objected and their request was granted, making the “reserve currency” the U.S. dollar. This meant that other countries would peg their currencies to the U.S. dollar, and—once convertibility was restored—would buy and sell U.S. dollars to keep market exchange rates within plus or minus 1% of parity. Thus, the U.S. dollar took over the role that gold had played under the gold standard in the international financial system. (Rogue Nation, 2003, Clyde Prestowitz)

Meanwhile, to bolster faith in the dollar, the U.S. agreed separately to link the dollar to gold at the rate of $35 per ounce of gold. At this rate, foreign governments and central banks were able to exchange dollars for gold. Bretton Woods established a system of payments based on the dollar, in which all currencies were defined in relation to the dollar, itself convertible into gold, and above all, “as good as gold”. The U.S. currency was now effectively the world currency, the standard to which every other currency was pegged. As the world’s key currency, most international transactions were denominated in US dollars.

The U.S. dollar was the currency with the most purchasing power and it was the only currency that was backed by gold. Additionally, all European nations that had been involved in World War II were highly in debt and transferred large amounts of gold into the United States, a fact that contributed to the supremacy of the United States. Thus, the U.S. dollar was strongly appreciated in the rest of the world and therefore became the key currency of the Bretton Woods system.

Member countries could only change their par value with IMF approval, which was contingent on IMF determination that its balance of payments was in a “fundamental disequilibrium”.

Also based on experience of inter-war years, U.S. planners developed a concept of economic security—that a liberal international economic system would enhance the possibilities of postwar peace. One of those who saw such a security link was Cordell Hull, the United States Secretary of State from 1933 to 1944. Hull believed that the fundamental causes of the two world wars lay in economic discrimination and trade warfare. Specifically, he had in mind the trade and exchange controls (bilateral arrangements) of Nazi Germany and the imperial preference system practiced by Britain, by which members or former members of the British Empire were accorded special trade status, itself provoked by German, French, and American protectionist policies. Hull argued

Unhampered trade dovetailed with peace; high tariffs, trade barriers, and unfair economic competition, with war…if we could get a freer flow of trade…freer in the sense of fewer discriminations and obstructions…so that one country would not be deadly jealous of another and the living standards of all countries might rise, thereby eliminating the economic dissatisfaction that breeds war, we might have a reasonable chance of lasting peace.